Thanks, the link "rtsp://admin:admin@192.168.1.108:554/live" work with VLC and the Media Player Classic included in K-Lite Codec Pack, I did not find the way to get the specific error, only cap.isOpened() return false. I use Wireshark but did not see any activity to that IP address. The same code, but using OpenCV-2.4.10 works witout problems.